It is known in the art that photographic display materials are utilized for advertising, as well as decorative displays of photographic images. Since these display materials are used in advertising, the image quality of the display material is critical in expressing the quality message of the product or service being advertised. Further, a photographic display image needs to be high impact, as it attempts to draw consumer attention to the display material and the desired message being conveyed. Typical applications for display material include product and service advertising in public places such as airports, buses and sports stadiums, movie posters, and fine art photography. The desired attributes of a quality, high impact photographic display material are a slight blue density minimum, durability, sharpness, and flatness. Cost is also important, as display materials tend to be expensive compared with alternative display material technology, mainly lithographic images on paper. For display materials, traditional color paper is undesirable, as it suffers from a lack of durability for the handling, photographic processing, and display of large format images.
In the formation of color paper it is known that the base paper has applied thereto a layer of polymer, typically polyethylene. This layer serves to provide waterproofing to the paper, as well as providing a smooth surface on which the photosensitive layers are formed. The formation of a suitably smooth surface is difficult requiring great care and expense to ensure proper laydown and cooling of the polyethylene layers. The formation of a suitably smooth surface would also improve image quality as the display material would have more apparent blackness as the reflective properties of the improved base are more specular than the prior materials. As the whites are whiter and the blacks are blacker, there is more range in between and, therefore, contrast is enhanced. It would be desirable if a more reliable and improved surface could be formed at less expense.
Prior art photographic reflective papers comprise a melt extruded polyethylene layer which also serves as a carrier layer for optical brightener and other whitener materials as well as tint materials. It would be desirable if the optical brightener, whitener materials and tints, rather than being dispersed throughout the single layer of polyethylene could be concentrated nearer the surface of the layer where they would be more effective optically.
Prior art photographic reflective display materials have light sensitive silver halide emulsions coated directly onto a gelatin coated opacified polyester base sheet. Since the emulsion does not contain any materials to opacity the imaging element, white pigments such as BaSO4 have been added to the polyester base sheet to provide a imaging element with both opacity and the desired reflection properties. Also, optical brightener is added to the polyester base sheet to give the sheet a blue tint in the presence of a ultraviolet light source. The addition of the white pigments into the polyester sheet causes several manufacturing problems which can either reduce manufacturing efficiency or reduce image quality. The addition of white pigment to the polyester base causes manufacturing problems such as die lines and pigment agglomeration which reduce the efficiency at which photographic display material can be manufactured. It would be desirable if the optical brightener, whitener materials and tints, rather than being dispersed throughout the polyester base sheet could be concentrated nearer the surface where they would be more effective optically and improve manufacturing efficiency.
Prior art reflective photographic materials with a polyester base use a TiO2 pigmented polyester base onto which light sensitive silver halide emulsions are coated. It has been proposed in WO 94/04961 to use opaque polyester containing 10% to 25% TiO2 for a photographic support. The TiO2 in the polyester gives the reflective display materials an undesirable opulence appearance. The TiO2 pigmented polyester also is expensive because the TiO2 must be dispersed into the entire thickness, typically from 100 to 180 μm. The also gives the polyester support a slight yellow tint which is undesirable for a photographic display material. For use as a photographic display material, the polyester support containing TiO2 must be tinted blue to offset the yellow tint of the polyester causing a loss in desirable whiteness and adding cost to the display material. It would be desirable if a reflective display support did not contain any TiO2 in the base and TiO2 could be concentrated near the light sensitive emulsion.
Prior art photographic display material use polyester as a base for the support. Typically the polyester support is from 150 to 250 μm thick to provide the required stiffness. A thinner base material would be lower in cost and allow for roll handling efficiency as the rolls would weigh less and be smaller in diameter. It would be desirable to use a base material that had the required stiffness but was thinner to reduce cost and improve roll handling efficiency.
In U.S. Pat. Nos. 6,270,950; 6,261,994; 6,093,521 and 6,083,669 the use of a voided polyester base material for imaging support materials is disclosed. The voided polyester disclosed is created utilizing polymer beads that cause voiding when the polyester sheet containing the polymer beads is oriented. The voiding generally is circular in shape and reduces the density of the polyester between 5 and 20%.
Prior art photographic bases are also know to contain oriented white reflective films that are adhesively adhered to a base substrate such as paper or plastic such as polyester. Such bases are coated with light sensitive silver halide photographic layers or with image receiving layers such as inkjet, thermal dye transfer and others. Typical imaging supports are disclosed in U.S. Pat. Nos. 5,866,282; 5,853,965; 5,888,681; 5,998,119; 6,043,009 and 6,218,059.